AP Bio test 3
Terms
undefined, object
copy deck
- feedback inhibition
- allows a cell to adapt to short-term fluctuations in the supply of a substance it needs by inhibiting the activity of enzymes
- regulation of enzyme production
- adjusts the amount of enzymes produced to adapt to long-term fluctuations in the supply of a substance it needs. this occurs at the level of transcription, the synthesis of mRNA coding for these enzymes
- coordinate control
- the ability to control a whole cluster of functionally related genes because they are in the same transcription unit and can be turned on or off with only one "switch"
- operator
- a segment of DNA that acts as a switch for a transcription unit, controlling the access of RNA polymerase to the genes. located within the promoter or between the promoter and the enzyme-coding genes
- operon
- the entire stretch of DNA that includes the operator, promoter, and the genes they control
- repressor
- a protein that can switch off an operon by binding to the operator and blocking the attachment of RNA polymerase to the promoter, preventing transcription oft he genes
- regulatory gene
- a gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes
- corepressor
- a small molecule that cooperates with a repressor protein to switch an operon off
- inducer
- a small molecule that inactivates a repressor by altering its confromation (changing its shape) to allow an operon to be transcribed into mRNA.
- inducible operon
- usually off but can be induced (turned on) when a specific small molecule (inducer) interacts with a regulatory protein (repressor)
- inducible enzymes
- enzymes with synthesis that is induced by a chemical signal
- repressible enyzmes
- enzymes with synthesis that can be repressed by a chemical signal
- cyclic AMP (cAMP)
- a small organic molecule made from ATP that is a common intracellular signaling molecule in eukaryotic cells (tells the cell about levels of a chemical like glucose within the cell). It is also a regulator of some bacterial operons
- catabolite activator protein (CAP)
- a regulatory protein that, when binded to cAMP, assumes its active shape and can attach to a specific site at the upstream end of a promotor
- activator
- a protein that binds to DNA and stimulates transcription of a gene
- differential gene expression
- the expression of different sets of genes by cells with the same genome
- histone acetylation
- the attachment of acetyl groups to certain amino acids of histone proteins. transcription proteins have easier access to genes in an acetylated region
- genomic imprinting
- a phenomenon in which expression of an allele is inherited from the male or female parent
- epigenetic inheritance
- inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence of a genome
- control elements
- segments of noncoding DNA that help regulate transcription by binding certain proteins
- enhancers
- groupings of distal control elements, control elements that are far from the promoter
- mediator proteins
- proteins that interact with other proteins, general transcription factors, at the promoter. these interactions help assemble and position the initiation complex on the promoter
- transcription initiation complex
- consists of the mediator proteins bound to the general transcription factors (other proteins) and the RNA polymerase II, which all interact at the promoter to speed up mRNA synthesis.
- silencer
- binds to the enhancer to reduce transcription
- alternative RNA splicing
- a type of eukaryotic gene regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns
- mRNA degradation
- mRNA will get eaten up by nuclease enzymes. if there is a longer poly-A tail, the message will not get destroyed as quickly. the length of the untranslated region (UTR) determines the lifespan of the message
- proteasome
- a giant protein complex that recognizes and destroys proteins tagged for elimination by the small protein ubiquitin